90 THE REPORT OF THE No. 19 



are found either on Burr or White Oak. (Quercus macrocaTpa and Quercus 

 alba). Common. 



Burr Oak Leafy-wreath Gall (Andricus topiarius, Ashm). Plate C, 

 fig. G. 



This gall resembles in external appearance the Goldenrod Bunch Gall 

 {Cecidomyia solidaginis). It consists of a cluster of dense, narrow leaflets 

 springing from a bud. When mature several small, brownish pupal cases 

 about 3 mm. long and 2 mm. wide can be seen among the leaflets, attached 

 at the base to the woody tissues below. The larvse are minute and whitish. 

 It occurs on the terminal twigs of the Burr Oak {Quercus macrocarpa) . Com- 

 mon. 



Oak Knot Gall {Andricus punctatus, Bass). Plate C, fig. 1. 



This is a rough, hard, woody, somewhat globular, knot-like gall en- 

 circling the stem and varying greatly in size, but commonly 1 to 2 inches in 

 diameter. The surface is ashy brown in color, and rough, with almost a net- 

 work of little ridges and depressions. Polythalamous. It occurs on the 

 branches of the Scarlet Oak {Quercus coccinea). Common. 



Oak Seed-Gall {Andricus seminator, Harr.). 



This is a woolly gall encircling the stem. It is irregularly oval, h to IJ 

 in. in diameter and | to 2 in. in length. Polythalamous, containing man> 

 cream-colored cases attached to the twig, each case looking very like an oat 

 seed. Early in the season the gall is white, but later it becomes brown. 

 Occurs on the twigs of the White Oak {Quercus alba), Puslinch Lake. Pare. 



Pine-cone Oak Gall {Cynips strobilana, 0. S.). Plate C, fig. 4. 



This gall is formed in the axil of a lateral bud just at the base of the 

 terminal bud-cluster. When viewed from some little distance, it appears like 

 a solid globular structure about | in. in diameter, but when more closely 

 examined it is found to consist of a rosette, or head of hard, brown, nut-like, 

 wedge-shaped structures fitting closely to one another and attached at the 

 base to a small spherical receptacle about i to J in. in diameter. Inside 

 of each of these nutlets there is a single chamber, containing but one white 

 Inrva. Occurs on the terminal twigs of the Burr Oak {Quercus macrocarpa). 

 Common at Guelph. 



Oak Fig Gall (Biorhiza forticornis, Walsh). Plate C, fig. 2. 



A group of many small, soft, bladder-like, one-celled structures, each 

 about 1-3 in. in diameter. These are often compared to a bunch or cluster 

 of pressed figs, but seem to me to resemble more nearly the honeycomb of the 

 bumble-bee, except that they are pale yellow in color, sometimes tinged with 

 red, turning yellowish brown in autumn. They are arranged in a cylindri- 

 cal cluster along the stem of the branches or twigs. The cluster is 1 to 2 in. 

 long and ^ to | in. in diameter. The interior of each one of these bladder-like 

 bodies is loosely filled with woolly fibres which keep in its position the small 

 larval cell. Occurs on the twigs of the White Oak {Quercus alba). Common 

 in some localities. 



Empty Oak Apple (Amphibolips inanis, 0. S.). 



This oak apple gall is very similar in external appearance to Amphi- 

 bolips confluentus (Harr.) but is considerably smaller and is quite dissimilar 

 in its internal structure. It is found on the under side of the leaf, and 

 springs from one of the main veins, is nearly spherical in form, about I — 5-6 

 in. in diameter, and has a smooth, glossy, light brown surface when mature, 

 which earlier in the season is green. The walls which enclose the almost 

 empty interior are very thin, somewhat parchment-like and brittle. The 

 small spherical larval cell within the cavity is about \ in. in diameter and 



